MT90812 Mitel Networks Corporation, MT90812 Datasheet - Page 24

• Manufacturer Part Number: MT90812
• Description: Integrated Digital Switch (IDX)
• Manufacturer: Mitel Networks Corporation

MT90812
6.1
Channel Attenuation is provided on incoming and outgoing channels that are in a conference. The gain can
range from +3 to -27 dB in steps of 1dB, as well as - dB for the incoming PCM data and +0 to -9 dB in steps of
3dB for outgoing PCM data. If an overflow condition occurs, then the input from each channel in a conference
can be independently attenuated, by setting the incoming channel attenuation bits in CMH for the specific
conference party. The outgoing gain bits are in the Conference Party Control register.
6.2
Channel inversion and noise suppression bits are specified in Connect Memory High for locations 60-6E
When noise suppression is enabled for a specific input channel, then the PCM bytes for this channel, when
below the selected threshold level, are converted to PCM bytes corresponding to the minimum PCM code level
before being added to the conference sum. The four threshold levels available correspond to the first, fifth,
ninth, and sixteenth step of the first segment. These are 1/4096, 9/4096, 16/4096, and 32/4096 with respect to
full scale A-law, and 1/8159, 9/8159, 16/8159, and 32/8159 with respect to full scale ulaw. The threshold level
is set using the threshold bits NS1, NS0.
The inversion bit allows for every other channel in a conference to be inverted. This reduces noise due to
reflections and line impedance mismatch.
6.3
As a party is added to a conference, if the insertion tone bit (IT) is set, all channels connected in a conference
will have the tone added to the conference output. This allows for conference users to be informed of a new
party being added to the conference, or to be reminded that they are in a conference.
The DM address of the desired tone must be programmed at location 6F
for mux-mode addressing). The tone source may be from any location in DM, including any of the 32 tones
from the Tone Generation block. The PCM data from the specified Data Memory location will be added to the
conference output for a specified tone duration.
The tone duration is specified in the Conference Control Register (CC). Refer to Section 22.10 for a description
of the Conference Control Register (CC). The tone duration can be set from 0.125 to 1.0 seconds in steps of
0.125 seconds. The tone duration is from the time the party is added to the conference by writing the
Conference Party Control Register.
20
Figure 15 - Conference Control with Conference Party Control Registers and Connect Memory
Channel Attenuation
Noise Suppression and Channel Inversion
Tone Insertion
30-3E
Incoming Channel
HEX
60-6E
CID,ST,IT,GCout
Conf Party Control
Control Registers
H*
Incoming Data
Conference Output
Data Memory
*in Non-mux micro-port mode the addresses for DM,CML and CMH are 060-06E, 160-16E and
260-26E respectively and the control registers addresses are 3B0-3BE. For mux-mode the addresses
DM,CML and CMH are E0-EE and the control registers addresses are 30-3E with the appropriate
page selected in the AMS register.
60-6E
6F
H*
H
GCin,Inv,NS
Gain
Parallel to Serial
High
Connect Memory
H
of CML, (16F
Insertion Tone
Incoming Channel
Output Stream
Advance Information
Low
H
non-mux mode, EF
H
.
H